Extremely high strength and work hardening ability in a metastable high entropy alloy

S S Nene; M Frank; K Liu; R S Mishra; B A McWilliams; K C Cho

doi:10.1038/s41598-018-28383-0

Extremely high strength and work hardening ability in a metastable high entropy alloy

Sci Rep. 2018 Jul 2;8(1):9920. doi: 10.1038/s41598-018-28383-0.

Authors

S S Nene¹, M Frank¹, K Liu¹, R S Mishra², B A McWilliams³, K C Cho³

Affiliations

¹ Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, Texas, 76207, USA.
² Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, Texas, 76207, USA. Rajiv.Mishra@unt.edu.
³ Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Grounds, MD, 21005, USA.

Abstract

Design of multi-phase high entropy alloys uses metastability of phases to tune the strain accommodation by favoring transformation and/or twinning during deformation. Inspired by this, here we present Si containing dual phase Fe₄₂Mn₂₈Co₁₀Cr₁₅Si₅ high entropy alloy (DP-5Si-HEA) exhibiting very high strength (1.15 GPa) and work hardening (WH) ability. The addition of Si in DP-5Si-HEA decreased the stability of f.c.c. (γ) matrix thereby promoting pronounced transformation induced plastic deformation in both as-cast and grain refined DP-5Si-HEAs. Higher yet sustained WH ability in fine grained DP-5Si-HEA is associated with the uniform strain partitioning among the metastable γ phase and resultant h.c.p. (ε) phase thereby resulting in total elongation of 12%. Hence, design of dual phase HEAs for improved strength and work hardenability can be attained by tuning the metastability of γ matrix through proper choice of alloy chemistry from the abundant compositional space of HEAs.